1. Field of the Invention
The invention relates generally to pouches, and more particularly to a former to form pairs of dispenser pouches of the flexible three-sided sealed type.
2. Description of Prior Art
With formers of this type, which are important elements of packaging machines for forming, filling and sealing three-sided, flexible pouches, the border areas of a foil strip approaching the former are bent over the non-folded wide center part of the strip and sealed lengthwise with said strip. This creates two connected tubes, which are first cross-sealed and filled, and then, using a suitable tool, separated in longitudinal direction for longitudinal cutting, or perforated in longitudinal direction. Generally a multiple of formers is arranged directly side-by-side, and the strips of a packaging material web, which were first appropriately cut lengthwise multiple times and are of the appropriate width, enter through said formers. Appropriately dimensioned filling pipes and forming pipes project into the former and the double tubes generated therewith.
A former of this type and/or a forming tool of this type is known from U.S. Pat. No. 6,006,501. A relatively short, specific fitting is attached directly to the lower end of said forming tool, and said fitting has a channel with a diameter that remains constant over the relatively short length of said fitting, with the channel corresponding approximately to that of a FIG. 8. The channel in the former itself has, when viewed in top view or in cross-section, the form of a slotted hole. With formers of this type, it was found that they only work somewhat acceptably with extremely thin and very flexible packaging material foil, which is also the case with the forming tool with the downstream fitting according to the aforementioned U.S. Pat. No. 6,006,501, because the foil material, which enters the downstream fitting from the direction of the former in slotted-hole shape, has to practically instantly adapt to the 8-shaped cross-section of the continuous channel in the fitting arranged below the former. In that way, the continuous channel in said downstream special fitting already corresponds to the desired final cross-section or the dispensing cross-section on the supply side of the packaging material web.
Accordingly, it is a general object of the present invention to provide an improved former, which already ensures when the foil material is wound onto the former, at the exclusion of an immediately downstream fitting, that the web already adapts successively to the typical 8-shaped final cross-section of the foil material double tube dispensed for lengthwise sealing.
It is a more particular object of the present invention to ensure an increasing approach of the two web edges to be bent to the foil material surface by the former already in the continuous channel by appropriately forming of the back wall of the continuous channel.
It is further a particular object of the present invention to arrange the back wall that delimits the continuous channel and two front walls arranged opposite said back wall such that the back wall and the front walls approach a middle plane that divides the continuous channel. It is a further and important object of the present invention that the dispensing area of the former is already designed such for the foil material that there is already a forming influence on the foil material in that area.
It is yet another particular object of the present invention to provide an improved former to allow the production of tube parts of various widths.
In accordance with the present invention, a former for a packaging machine is provided, to form pairs of three side sealed pouches from packaging foil material comprising a fitting with a channel that is open on the top and bottom and partially open toward the front; arranged in the channel are two facing, parallel running form- and filling pipes; the channel has an upper supply edge for the web; the back wall of the channel runs from the supply edge to the dispensing opening of the former; the form of the bent side walls of the channel is adapted to the round form of the form- and filling pipes and together with said pipes and the front walls of the channel forms a gap for receiving, bending and folding one strip of the foil material passing the channel; the front walls of the channel have form edges, which form edges, when bent, continually attach to the foil supply edge and delimit behind the bent connection a section converging in the continuous foil direction; at the end of said section, the front walls delimit a slit and the front walls of the channel are developed on the outside in the form of shawl-collar-like foil tail surface running out at the slit, whereby the improvement is that the back wall and the form edges of the front walls, proceeding from the foil supply edge and the converging section to the end of the downwardly open slit, are developed relative to one another with steady approximation.
Because of this development of the former in accordance with the present invention and in connection with the two filling pipes that punch through the continuous channel, the packing strip approaching said former is already formed into the final form of the double tube from the supply edge of the foil material continuously and without deformation. After leaving the fitting, the foil strip edges placed on the back wall of the foil strip are sealed lengthwise in the known manner. A fitting arranged at the lower end of the former according to U.S. Pat. No. 6,006,501 is thereby advantageously avoided.
With respect to the feature that the back wall and the front walls approach one another relatively up to the end of the former, relative should be understood such that the back wall can approach the front walls, or also that the back wall and the front walls can jointly approach an imaginary, vertical middle longitudinal plane of the continuous channel.